First, that modern desktop operating systems are anything but. They are bloated, slow, and layered with legacy cruft that still functions only thanks to Moore's Law. Second, that innovation in desktop operating systems stopped about 15 years ago and the major players are unlikely to heavily invest in them again. And finally, I hope to convince you that we can and should start over from scratch, learning the lessons of the past.
As it becomes a more general-purpose machine, the iPad will continue to steal uses and users from the Mac. As often stated by its execs, Apple isn’t worried about cannibalization. More important, the iPad’s ever-improving UI and functionality will wrest users from its competitors.
This leaves the Mac line doing nicely for two disconnected reasons: High-end “truck-like” applications, and the estimable population of users who, as a matter of personal preference, opt for the traditional “horizontal-hands” UI.